Adding a small inverter

I would like to add a small (300w) inverter to my M35A2
Where would You tap into the system ? I was planning on putting it the cab to keep it cooled and out of the weather. I was looking at the cables to the slave receptacle, but am not convinced. By my calculations it probably only draws 12.5 amps, so the wiring gauge is not unreasonable. Thanks

I have a 800W from HF and it is working fine. I also have a 2000W inverter too and no issue at all. Go to HF site and down coupons for like 20% off. I think 300W is too low. U should get double what it requires. For example a 300 W 12V heater, I would get at least 600-800W to power that...

I agree with Lextreme - go big with inverters. Most of them are junk, and will not provide the rated output for very long.

Oh, and hello Poison Ivy! 4th Infantry! My old outfit!

I would use the large eyelet connectors on the end and go right to the bolts on the batteries with an inline fuse. Gimpy and I worked on a truck direct from GL that had wires attached directly to the batteries without a fuse that ran into the cab. Not good.

I agree with the double the size needed philosophy.

I connected to my 24v system and transformed down to 12v (for 12v accesories and then pulled off that) that way the load is balanced across the batteries. I agree you should go minimum 1000 watts. I always oversize my cables also for better DC load carry. In one deuce I put in backup batteries with 12v parallel that can be charged from the cab with a switch (off the transformed 24vdc to 12vdc). They run the 5kw inverter. This allows for greater loads if needed by pulling off of the main batteries if need be also. As said above fuse everything and you can buy transformers relatively cheap.

63C20 said:

I would like to add a small (300w) inverter to my M35A2
Where would You tap into the system ? I was planning on putting it the cab to keep it cooled and out of the weather. I was looking at the cables to the slave receptacle, but am not convinced. By my calculations it probably only draws 12.5 amps, so the wiring gauge is not unreasonable. Thanks

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What will it be used for?

Inverter? Are you trying to drop voltage to 12 or up them to 110? If you are a 12 to 110 you will need a 24 to 12 inverter or batt equalizer.

stampy said:

I connected to my 24v system and transformed down to 12v ... you can buy transformers relatively cheap.

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Hmmm. Transformers don't work with DC, so I'm guessing you are using the wrong term.

Can you describe what you're talking about?

I am only planning on using mine for recharging my cell phone and running a GPS while driving. Even so, I'm doing the overkill thing with a 650 watt inverter. It will also safely run my laptop if I need it, which is also a good thing.

Not a good idea to tap between two batteries and suck out 12 volts due to the fact the batteries will not charge at the same rate. It took me a while to realize that and only did so with the help of SS folks here.

You can get a battery equalizer off ebay for $100 used. It is a takeoff. It's what I did and I now have 12 vdc, or 24vdc at my disposal, where I run the two voltages to two seperate fuse terminal blocks on the fire wall. From there you can tap into it and get whatever source voltage you want.

Or, you could just do it the easy way and tap in the middle of the two batteries and take the chance of ruining your batteries.

I would just mount it on the firewall, high up and out of the way. Do be sure to use fuses either way. Those voltages will arc weld your firewall and cause a fire you cannot stop once started until your wiring melts down, and even then, it might just cause a second fire in another location.

Both of these have comments from people using them on MVs, including a comment on why you don't want to tap off one of your batteries instead of using both.

http://www.amazon.com/Pyle-PSWNV720...55583924&sr=8-2&keywords=24v+to+12v+converter

http://www.amazon.com/Samlex-America-SDC-23-Amp-Converter/dp/B0002D6KO0/ref=pd_cp_e_3

If you get an inverter, get a 24v one. No need to mess with 12v crap. Mine is a 1500watt that I plug into the slave cable port when needed. If I were to hook it up permanently, I would run the wires through the holes in the cab, behind the pass seat, near the slave cables. Make sure you have a gasket in the holes, you don't want the wires grounding out!

MarcusOReallyus said:

Hmmm. Transformers don't work with DC, so I'm guessing you are using the wrong term.

Can you describe what you're talking about?

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Ok Ebay has tons of examples.

I guess to be REALLY technical you aren't REALLY TRANSFORMING as much as you are stepping the voltage down to 12v from 24v. But I have no idea what you would call it. To step voltage up it was called a buck and boost transformer.

I too have used 24v inverters successfully just make sure to get one with US plugs

stampy said:

I guess to be REALLY technical you aren't REALLY TRANSFORMING as much as you are stepping the voltage down to 12v from 24v.

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That's not being "technical" that's being correct. That's a converter, not a transformer, and it doesn't matter how many foreigners call it the wrong thing on their website, it's still a converter.

Calling that thing a transformer is like calling a transmission a transfer case. They are two different things with two different functions.

stampy said:

I too have used 24v inverters successfully just make sure to get one with US plugs

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That's sure a lot better solution than using a converter to get 12 volts then an inverter to get 120. Definitely the right way to go for 24v vehicles.

cranetruck said:

What will it be used for?

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I have some experience with inverters and have an Aims 300 watt pure sine wave 24 volt inverter. I plan on running some small electronics and laptop charging. I don't need much capacity. The large cheap modified sine wave inverters have poor quality power and some Serious power requirements. A 1000 watt inverter will require 42 amps at 24 volts

The 300 Watt inverter can pretty much be hooked up anywhere since most wiring on the truck is 14 or 16 gauge.
Good to see that you have a pure sine wave type, modified sine wave will create unwanted noise...

To clarify a couple of things mentioned here. You can't transform DC, only AC. Inverters are typically used to convert low voltage DC to high voltage AC. Converters or regulators are used to convert or regulate one DC voltage to a lower DC voltage although there are some new converters called Boost converters that will output higher DC voltages than they take in.

To tap 12 volts from a 24 volt system is fairly easy to do but hooking the 12 volt lead between the frame ground and the battery mid span tap will work but can cause an imbalance in the electrical system that drains one battery before the other. Tapping 12 volts between the mid battery tap and the high side battery can result in fires if have a device with the ground wired to the case and the case shorts to ground. Most radios are built like this.

Another way to get 12 volts in a vehicle is by using either a converter that connects across the 24 volt system and regulates that down to 12 volts. This will draw current equally from both batteries keeping the system in tune.

Probably the best way to get 12 volts is by using a battery equalizer. An equalizer measures the voltage across both batteries and makes sure they stay balanced while providing plenty of 12 volt power safely. PulseTech and Vanner both make some excellant equalizers specifically for this purpose. They can be a bit pricey though unless you find them on a site like eBay. Here's a PulseTech equalizer like the one I have installed in my HMMWV. Plenty of fused taps for 12 volts while maintaining the charge across the batteries. List on this is over $800! and it's on eBay for $39!

http://www.ebay.com/itm/Pulse-Tech-...Parts_Accessories&hash=item35be5ee6f2&vxp=mtr

Kurt

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